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STIM2 is designed to deliver scientific stimuli with all the quality our customers have come to expect from Neuroscan.

Operating under Windows® XP, Stim2 provides a familiar and simple interface to design and deliver stimuli with ease and, more importantly, accuracy. Stim2 provides complete control of the experiment, while delivering the highest quality stimuli. Stim2, like the original STIM system, is a comprehensive stimulus presentation system consisting of a library of sensory, cognitive and neuropsychological tasks. It is a modern tool that provides well-defined and widely known paradigms that may be used as a stand-alone package, or integrated fully with psychophysiological acquisition systems such as our SCAN 4

EEG/EP workstation, by providing synchronized trigger pulses. Stim2 is a contemporary version of the original system, with greater flexibility and ease of operation with a familiar Window’s® interface. Whether the user’s interests lie with basic sensorimotor and perceptual tasks, more complex recognition tasks, or the most sophisticated cognitive processes, Stim2 can deliver the stimuli with the precision needed for accurate analysis.

Task Library - Fourteen tasks are pre-programmed into the Stim2 software to provide a task library to build upon. Each task allows the user to modify parameters, such as, the duration, order of presentation, the interstimulus interval, performance feedback options, and many more. The programs are categorized into Motor, Perceptual, Attention, Memory, and Cognitive tasks. Some of the more common tasks include Finger Tapping, Stroop, Card Sorting, and Categories tasks from neuropsychology. Additional tasks include Pattern reversal, Naming, Visual tracking, Spatial memory, VIsual and Auditory continuous

performance, Verbal learning, and Visual memory tasks.

Task Generation – Creating custom tasks with ease is the most important element in a stimulus program. The Gentask utility program provides an effective tool to create the user’s own tasks with no programming skills required.

Image and Sound Files - Moving into the Windows® XP environment has allowed a major advance in the types of stimuli that can be delivered. Common audio (including WAV and Neuroscan SND files) and video (including JPG, BMP, PCX, PNG, TIF, CUT, etc., files) are easily presented. The user can create their own sounds using the Sound Editor and convert graphics file type to one handled by Stim2 using the Image Converter. Audio and visual stimuli can be presented simultaneously while having flexibility in the placement of the trigger pulse in relation to a stimulus.

Compatibility – Gentask files from the original STIM are read automatically in Stim2. Existing SND, CUT and PCX files from STIM are also read by Stim2, with no conversion required.

Data Analysis – Behavioral data (performance results) from the tasks are available for review in the Internet Browser, and the DAT file versions of these files can be transferred to SCAN for integration with the EEG data files (as with STIM).

Accuracy - Accuracy is dependent upon the variation of the Stim2 system the user has, as well as the computer hardware. The Stim2 (Stim2 Complete) system with the STIM Audio System Unit provides the greatest possible timing accuracy, with virtually no error for visual stimuli and with variance less than one millisecond for audio files. The Stim2 (Stim2 Software Only) system with no hardware is more variable, and timing variation will depend on computer speed, the video card, and especially the audio board in the computer.

The decibel level (SPL) for audio stimuli is adjustable by .75db steps, if you have the STIM Audio System Unit. The software only version requires a decibel meter for SPL measurement.

Integration –Stim2 will integrate with fMRI, ERP and other recording devices, allowing the user to trigger external devices (such as an SEP stimulator or MRI), or for external devices to trigger Stim2 (Stim2 with hardware version only). The seamless integration with Neuroscan data acquisition products allow on-line averaging, sorted averages based on trial type, accuracy and latency of responses, and sequence recognition (using BATCH commands).

Gentask Editor – One of the most popular programs in STIM is the Gentask Utility program, since it allows maximum control over stimulus presentation. The heart of Gentask is a "sequence file", a line-by-line program that governs many aspects of stimulus presentation.

Stim2 features a Gentask Editor that makes creating and modifying sequence files much easier.

In the sequence file, the user can set the duration of presentation, the time allowed for a valid response, the interval between stimuli, the position of the graphics file on the screen, the decibel levels for audio files (independent left and right channel settings), the correct expected response, and the trigger type code sent to the acquisition system, for each stimulus that is presented. A new drag-and-drop feature

allows the user to add lines to the file with maximum ease. Additional options with the sequence file include flow control and conditional branching commands, counters, ways to build more complex stimuli, increasing/decreasing difficulty levels based on past performance, mask options, noise options, and many more.

The Stim2 Audio System and Response Interface

Each Stim2 Complete system is provided with precision hardware for recording sounds from a microphone or line input with 16 bit A/D conversion, playing back mono or stereo sounds at SPL calibrated levels (HL also possible), recording manual responses with push buttons or optional finger-lift LED photocells, recording verbal responses with millisecond accuracy, and measuring reaction time with an independent clock in case stimulus and response occur simultaneously. Other features of the STIM Audio System include anti-aliasing filters, audiometric quality insert earphones, independent left and right channel gain levels, and more.

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